let year = 2000;

function isLeapYear(year) {
    if (!(year % 400)) {
        return `${year} is a leap year.`;
    } else if (!(year % 100)) {
        return `${year} is not a leap year.`;
    } else if (!(year % 4)) {
        return `${year} is a leap year.`;
    } else {
        return `${year} is not a leap year.`;
    }
}

let result = isLeapYear(year);
console.log(result)